The Teeth of Herbivores, Carnivores and Omnivores Home » The Teeth of Herbivores, Carnivores and Omnivores The Teeth of Herbivores, Carnivores and Omnivores All animals have teeth that are adapted to eating certain types of food. For instance, herbivores, because they are plant eaters, have strong and flat molars that are made for grinding leaves and small or non-existent canine teeth. Carnivores, the meat eaters of the animal world, have very defined canine teeth for tearing at meat, combined with a sometimes limited number of molars. Omnivores, because they eat both meat and plants, have a combination of sharp front teeth and molars for grinding. Herbivores have teeth that are highly specialized for eating plants. Because plant matter is often difficult to break down, the molars of herbivores are wider and flatter, designed to grind food, and aid in digestion. Herbivore incisors are sharp for tearing plants, but they may not be present on both the upper and lower jaw. White tail deer are a perfect example of an herbivore that has only lower incisors and a rigid upper jaw that assists in the tearing of plants.

Many animals, such as horses and cows, have jaws that are capable of moving sideways. Elephants are herbivores, and their incisors are unlike those found in other animals. Odd as it may sound, a tusk is actually a tooth, an incisor, that has evolved into a different type of tool, often used for defense. Animal Adaptations - This pictorial guide compares the teeth of herbivores and carnivores. What is an Herbivore? - Learn about where herbivores fit in the food chain, as well as which types of food they might eat. Herbivores: Teeth for Grazing - The U.S. Department of the Interior explains the characteristics of herbivores, and where they fit in ecosystems. NatureWorks - Learn how herbivores can be different from one another, even though they all eat plants. Carnivores have a set of teeth that are very different from herbivores'. This makes sense, because they also have a different diet. A carnivore will use its teeth to kill a prey item before eating it. The sharp incisors and pointed canine teeth are perfectly designed for both incapacitating and eating a meal.

A canine tooth can be easily identified, as it is the longer, pointed tooth located on either side of the incisors. The molars are fewer in number than other animals may have, mainly because so much of the work is done by the teeth in the front of the mouth. While the presence of canine teeth does not guarantee that an animal is a carnivore, it is an indicator that meat is some part of the diet. Animal Diversity Web - Here, you can discover information about carnivores, including their ranges, habitats, and diversity. Introduction to Carnivora - This page includes information about carnivores, from their fossil history to systematics and morphology. What is a Carnivore? - Here, you'll find information about carnivores and the role they play in their ecosystems. Big Is Not Bad - Large carnivores are suffering the effects of range loss, and might benefit from efforts aimed at preservation. Humans are omnivores, meaning we eat a variety of foods, including meat and plant matter. A quick glance at your own teeth will give you a sense of the variety of shapes and sizes of teeth an omnivore can have. Human teeth are not indicative of exactly what you will see in the mouth of all omnivores.

Each omnivore will have teeth that are specifically adapted to the diet these animals consume. Animals with teeth like humans that use their molars for grinding and their incisors and canines for ripping or tearing are said to have heterodont dentition. Each tooth is designed for a specific role in processing the food eaten. Homodont dentition, found in most omnivorous reptiles, occurs when the teeth are all relatively the same size and shape. These teeth are used more for the acquisition of food than for the processing of that food. Are Humans Omnivores? - This page includes information regarding the opportunistic tendencies of omnivores to eat whatever is available when hunger strikes. Omnivores - This is an introduction to omnivores, along with an explanation of how some animals may start life as herbivores and then become omnivores later in life. You Eat What? - This page discusses the differences between omnivores, herbivores and carnivores, including where they find their food. How to Be a Healthy Omnivore - This page explores whether there are choices that allow better health while eating as an omnivore. Certain animals are equipped with teeth that are suited to the consumption of a particular diet.

Carnivores, herbivores, and omnivores may have some overlap in the size and shape of teeth, but looking at all of the teeth in the jaw will give you a good idea of the food types each animal relies on. It is possible to identify an animal just by looking at the skull and the placement of the teeth. Dental Procedures & Cosmetics Teeth: Facts (Science Trek: Idaho Public Television) Videos Teeth: Facts Smile! Show off those teeth. Strong teeth are a sign of good overall physical health. Without them, you can't eat or even speak well. Your teeth are important. What Is a Tooth? Teeth are like bones. They are alive. They start forming before you are born and continue to develop until you are an adult. Teeth form inside the jaw and are nourished and protected by the pink tissue that surrounds them. That pink tissue is called the gums. The crown is the part of the tooth you can see above the gums, but there is a lot more to your teeth. The tooth is made up of five parts. The enamel is the white covering on the top. It is the hardest substance in your whole body. The layer under the enamel that you can't see is the dentin .

It makes up most of the tooth and isn't as hard as the enamel. The pulp is under the dentin and it is the softest part of the tooth. It is made up of nerves and blood vessels. It is what hurts when you get a toothache. The root is what holds the tooth in place and a thin layer of tissue called the clementum protects it. How Many Teeth? Kids have about 20 teeth by the time they turn 3 years old. This first set of teeth are called milk teeth, baby teeth or primary teeth. By the time you are five or six, your first permanent teeth will start coming in. The permanent teeth lie just beneath the roots of the baby teeth. As a permanent tooth grows, it puts pressure on the baby teeth. That pressure causes the root of a baby tooth to dissolve and the baby tooth falls out. The permanent tooth then moves into place. By the time you are an adult, you should have 32 teeth. Mammal Teeth Mammal teeth are called heterodonts , meaning they have two types of teeth — the primary teeth and the permanent teeth. Mammals have four types of teeth, each with a specific task to handle for different kinds of food.

Incisors are used for cutting. Canines are for tearing. Premolars are used for crushing, and molars are used to grind up food. Not all mammals have all, or even any, of each kind of tooth. It all depends upon what kind of food the animal eats. Humans have: Eight incisors — four in your upper jaw and four in your lower jaw in the front of your mouth. Incisor means “biting tooth” and these teeth help you bite into your food. Four canines — two in your upper jaw and two in the lower jaw. Your canines are located next to the incisors. Canine means “like a dog.” These teeth are pointed and are used to stab and tear at food. Eight molars — four in your upper jaw and four in your lower jaw. These teeth in the back of your mouth help you grind your food. Different Kinds of Animals Have Different Types of Teeth Carnivores need long canine teeth so they can grip and kill prey quickly. Their incisors strip flesh from bones. They don't need molars for grinding food. They have teeth that slice meat — these are called carnassial teeth, not molars.

Herbivores do not have upper incisors because they cut the plants with their lips instead. All herbivores need their molars (the big flat teeth at the back of the mouth) for grinding the mouthfuls of food. A herbivore's molars are big and ridged for better grinding. Omnivores have teeth that are used for many different things. Like grasping, cutting, grinding, and slicing. This is especially true for humans. Yes, humans are omnivores, meaning they eat meat, fruits and veggies! Insectivores have teeth that are square with sharp points that are perfect for tearing up insect bodies. Taking Care of Your Teeth Ancient Egyptians believed that a mixture of onions, spices and incense would cure a toothache. Today, we know that toothaches happen when you don't take care of your teeth. When you eat, bits of food particles are left on your teeth. When sugars combine with bacteria in your mouth, plaque forms. The plaque forms acids that can eat a hole in the tooth. This is called a cavity . Left untreated, the cavity can spread into the dentin and then into the pulp.

If bacteria gets into the pulp, it can cause the blood vessels to swell and press on the nearby nerves. Ouch! Now you have a real toothache. Do animals get cavities? You bet! Especially if they don't take care of their teeth. Even animals get cavities! Check out the bear's filling! Plaque can also harden into a chalky substance called tartar . Tarter can cause gum disease. If your gums aren't healthy, they can't protect your teeth. If the gum disease gets really bad, you can lose a tooth. And gum disease can also lead to other health problems like heart disease and strokes. So taking care of your teeth is important for your whole body! Keeping Your Teeth Healthy You can prevent cavities and gum disease by brushing at least twice a day. You should use a fluoride toothpaste and a toothbrush with soft, rounded bristles. Brush with short, angled strokes. Brush the front and back sides of your teeth and don't forget to brush your tongue too! That will help keep your breath fresh. When brushing, you should brush for 2 minutes on your upper teeth and 2 minutes for your bottom teeth. You should brush in the morning, the evening, and after eating meals!

Be sure to rinse your brush well and get a new brush every three months. No time to brush after a meal? Be sure to rinse your mouth out well with water to help clean away as many food particles as possible until you can get to your toothbrush! Besides, germs love a dry mouth. So, if you drink lots of water to help wash away leftover foods, there will be fewer places for bacteria to grow! Besides brushing, you should also floss once a day. Flossing removes food and plaque from between your teeth — places your toothbrush cannot reach. This is also a great way to help prevent gum disease. You should also make regular visits to your dentist and eat right. Candy and other sticky, sugary foods are bad for your teeth. Eating a good healthy diet, brushing and flossing often, and visiting your dentist regularly are the best way to keep a healthy smile! Going to the Dentist Even if you don't have a toothache, you should visit your dentist at least twice a year to check your teeth. When you visit the dentist she will examine your teeth and gums, and either the dentist or the dental hygienist will clean your teeth to remove the plaque and tartar from your teeth.

Dentists and hygienists use special tools to clean and check your teeth. The dentist will use an explorer to check and clean around your teeth. It is a metal tool with a hook on the end. Dentists also use a small suction tube to suck the water and saliva out of your mouth. The dentist will also use a mirror to help get a better look at all the surfaces of your teeth. If the dentist finds any cavities they will take an X-ray of your teeth, remove the decayed part of the tooth and put in a filling to prevent further decay. Piece of cake! Well, maybe that's not the best choice of words . . . but going to the dentist is pretty painless these days! Wild and Wacky Facts Who has the most teeth? On land the mammal with the most teeth is the Giant Armadillo, which can have as many as 100 teeth in its jaws. In the oceans the real tooth master is the long-snouted spinner dolphin. They can have as many as 252 teeth in their long thin jaws. These teeth are more like reptile teeth because they are all the same basic shape, thin sharp little spears.

These teeth are good for catching and holding the little fishes that dolphins eat. Shark lose teeth throughout their life and they grow new ones to replace the lost teeth. As soon as one falls out, another one takes its place. Poisonous snakes have specialized teeth called fangs. Fangs are hollow teeth that pierce skin and inject poison. Rats gnaw all the time to help wear down their teeth. If they didn't wear down them down, their bottom teeth would continue to grow longer — potentially right into their brain. Some animals dig with their teeth, while others use their teeth for self-defense or displays of power, such as when males fight for territory or for females. Wild pigs dig with their tusks, which are actually canine teeth. Even the mighty walrus will use its large canine teeth to anchor itself to ice while sleeping. Can you believe this? Our first president, George Washington, did not have teeth made out of wood, but he did have teeth made out if hippopotamus teeth. He also had teeth made out of ivory, lead, human teeth, and cow and sheep's teeth. In the early 1600s, Japanese women blackened their teeth. They thought it showed loyalty to their husbands. Eww .

. . yuck! In the ninth century, Mayans filed their teeth into different shapes and decorated them with jewels. Today, some people get “grillz” to impress their friends. What do you think? Think jewelry on your teeth is cool? Maybe, but not if you wear it for an extended period of time — it can cause tooth decay and gum disease. So, if you do add some sparkle to your smile, be sure to take care of the teeth underneath so you don't lose all your shine! Dental and Skull Anatomy of Carnivores, Herbivores, and Omnivores Fun Stuff Dental and Skull Anatomy of Carnivores, Herbivores, and Omnivores An animal’s diet is one of the most important aspects of its biology, and it helps shape the behavior, evolution, and anatomy of the species. The development and arrangement of an animal’s teeth, known as its dentition, reflects this best; but an animal’s skull evolves to suit its diet as well. In general, meat-eating carnivores have teeth for tearing and skulls capable of biting with great force, while the plant-eating herbivores have teeth and skulls equipped to grind tough vegetation.

Omnivores, which eat both plants and animals, have skulls and dentition suitable for a wide range of foods. These trends are so strong that paleontologists can often determine the diet of an extinct animal from nothing more than a few teeth or skull fragments. Carnivores Carnivorous animals subsist on the flesh, bones, and viscera of other creatures. Most carnivores have long, sharp teeth adapted to ripping, tearing or cutting flesh. While many also possess a few molars in the back of their mouths, and sharp incisors in the front, the most important teeth for carnivores are their long, sharp canine teeth. Carnivores drive these teeth through the flesh of their prey with the help of very large temporalis muscles, which are responsible for pulling the lower jaw upwards and backwards towards the skull. The temporalis muscles attach to the jaw at one end, and the top of the skull at the other end. To help accommodate larger temporalis muscles, some predators have evolved to have an enlarged ridge, termed the sagittal crest that acts as an attachment point or anchor for the muscle. However, the sagittal crest is not exclusively limited to carnivores, as it also appears in many herbivorous primates as well.

Additionally, because predators must capture and kill their food before they can eat it, some possess teeth that aid in prey capture. Cats, for example, use their four, long canine teeth to sever their prey’s spinal cord. Some snakes have even more specialized prey-capturing teeth that have evolved into hypodermic-needlelike fangs to deliver venom into their prey. Herbivores Herbivores survive by consuming plant material. While some are indiscriminate grazers that consume a variety of plants, others are specialists that only eat a single plant species. For example, goats may eat virtually any vegetation they encounter, but koalas subsist entirely on eucalyptus plants. In general, plant foods are difficult to breakdown and digest; so, many herbivores have several pairs of broad molars that they use to grind leaves, shoots, and twigs. Often, herbivores feature ridged molars and jaws capable of moving sideways. Both of these traits help herbivores to grind their food more effectively. Most herbivores are missing canines entirely, and those that do possess them usually have very small or reduced canines that are not very important for chewing food.

Some herbivores have large incisors for clipping or tearing vegetation, but they may only occur on the lower jaw. For example, most deer lack upper incisors and press their lower incisors against their hard, upper palate to rip twigs and branches from trees. By contrast, horses have both upper and lower incisors that they use to clip vegetation cleanly. Some herbivores have evolved teeth that are no longer involved in feeding at all. For example, the large tusks of elephants are highly modified incisors. Elephants use their tusks to manipulate items in their environment, dig for water, and defend themselves. Walruses and some pigs also feature incisors that have evolved into tusks used for foraging, defense, and intra-species combat. Omnivores Omnivores, such as raccoons, opossums, bears, and humans, are animals that consume both plant and animal material. Accordingly, omnivores have dentition, skulls, and teeth suitable for handling a variety of foods. Most omnivores have evolved different types of teeth, located in different parts of their mouths. In such scenarios, each type of tooth excels at handling a different type of food.

For example, humans use their incisors and canines for ripping and cutting, and their molars and premolars for grinding. Biologists describe animals with such teeth as having heterodont dentition. By contrast, the teeth of homodont animals, such as iguanas, are all the same shape. As with some carnivores that have teeth to aid in prey capture, some omnivores have teeth that help them to obtain, rather than process, their food. Rodents are famous for their long, continuously growing incisors, which they use to chew through husks, shells and wood. This allows them to access well-protected or difficult-to-access foods, such as nuts. Although rodents are omnivores that occasionally eat insects and scavenge carcasses, plant material makes up the bulk of their diet. Their dentition reflects this as well: Rodents have strong molars, yet lack canine teeth entirely. Instead, rodents have a gap between their incisors and molars, termed a diastema.

References Anatomy and Physiology of Animals/The Gut and Digestion - Wikibooks, open books for an open world Anatomy and Physiology of Animals/The Gut and Digestion From Wikibooks, open books for an open world original image by vnysia cc by Contents After completing this section, you should know: what is meant by the terms: ingestion, digestion, absorption, assimilation, egestion, peristalsis and chyme the characteristics, advantages and disadvantages of a herbivorous, carnivorous and omnivorous diet the 4 main functions of the gut the parts of the gut in the order in which the food passes down it The Gut And Digestion[ edit ] Plant cells are made of organic molecules using energy from the sun. This process is called photosynthesis. Animals rely on these ready-made organic molecules to supply them with their food. Some animals (herbivores) eat plants; some (carnivores) eat the herbivores. Herbivores[ edit ] Herbivores eat plant material. While no animal produces the digestive enzymes to break down the large cellulose molecules in the plant cell walls, micro-organisms' like bacteria, on the other hand, can break them down.

Therefore herbivores employ micro-organisms to do the job for them. There are three types of herbivore: The first, ruminants like cattle, sheep and goats, house these bacteria in a special compartment in the enlarged stomach called the rumen. The second group has an enlarged large intestine and caecum, called a functional caecum, occupied by cellulose digesting micro-organisms. These non-ruminant herbivores include the horse, rabbit and rat. Humans also have a cecum and can be classified as the third type of herbivorous class, along with orangutans and gorillas. Plants are a primary pure and good source of nutrients, however they are digested very easily and therefore herbivores have to eat large quantities of food to obtain all they require. Herbivores like cows, horses and rabbits typically spend much of their day feeding. To give the micro-organisms access to the cellulose molecules, the plant cell walls need to be broken down. This is why herbivores have teeth that are adapted to crush and grind. Their guts also tend to be lengthy and the food takes a long time to pass through it. Eating plants have other advantages.

Plants are immobile so herbivores normally have to spend little energy collecting them. This contrasts with another main group of animals - the carnivores that often have to chase their prey. Carnivores[ edit ] Carnivorous animals like those in the cat and dog families, polar bears, seals, crocodiles and birds of prey catch and eat other animals. They often have to use large amounts of energy finding, stalking, catching and killing their prey. However, they are rewarded by the fact that meat provides a very concentrated source of nutrients. Carnivores in the wild therefore tend to eat distinct meals often with long and irregular intervals between them. Time after feeding is spent digesting and absorbing the food. The guts of carnivores are usually shorter and less complex than those of herbivores because meat is easier to digest than plant material. Carnivores usually have teeth that are specialised for dealing with flesh, gristle and bone. They have sleek bodies, strong, sharp claws and keen senses of smell, hearing and sight. They are also often cunning, alert and have an aggressive nature. Omnivores[ edit ] Many animals feed on both animal and vegetable material – they are omnivorous.

Most primates are herbivorous but a few, such as chimpanzees and humans, belong to this category as do pigs and rats. Their food is diverse, ranging from plant material to animals they have either killed themselves or scavenged from other carnivores. Omnivores lack the specialised teeth and guts of carnivores and herbivores but are often highly intelligent and adaptable reflecting their varied diet. Treatment Of Food[ edit ] Whether an animal eats plants or flesh, the carbohydrates, fats and proteins in the food it eats are generally giant molecules (see chapter 1). These need to be split up into smaller ones before they can pass into the blood and enter the cells to be used for energy or to make new cell constituents. For example: The Gut[ edit ] The digestive tract, alimentary canal or gut is a hollow tube stretching from the mouth to the anus. It is the organ system concerned with the treatment of foods. At the mouth the large food molecules are taken into the gut - this is called ingestion. They must then be broken down into smaller ones by digestive enzymes - digestion, before they can be taken from the gut into the blood stream - absorption. The cells of the body can then use these small molecules - assimilation.

The indigestible waste products are eliminated from the body by the act of egestion (see diagram 11.1). Diagram 11.1 - From ingestion to egestion The 4 major functions of the gut are: 1. Transporting the food; 2. Processing the food physically by breaking it up (chewing), mixing, adding fluid etc. 3. Processing the food chemically by adding digestive enzymes to split large food molecules into smaller ones. 4. Absorbing these small molecules into the blood stream so the body can use them. The regions of a typical mammals gut (for example a cat or dog) are shown in diagram 11.2. Diagram 11.2 - A typical mammalian gut The food that enters the mouth passes to the oesophagus, then to the stomach, small intestine, cecum, large intestine, rectum and finally undigested material exits at the anus. The liver and pancreas produce secretions that aid digestion and the gall bladder stores bile. Herbivores have an appendix which they use for the digestion of cellulose.

Carnivores have an appendix but is not of any function anymore due to the fact that their diet is not based on cellulose anymore. Mouth[ edit ] The mouth takes food into the body. The lips hold the food inside the mouth during chewing and allow the baby animal to suck on its mother’s teat. In elephants the lips (and nose) have developed into the trunk which is the main food collecting tool. Some mammals, e.g. hamsters, have stretchy cheek pouches that they use to carry food or material to make their nests. The sight or smell of food and its presence in the mouth stimulates the salivary glands to secrete saliva. There are four pairs of these glands in cats and dogs (see diagram 11.3). The fluid they produce moistens and softens the food making it easier to swallow. It also contains the enzyme, salivary amylase, which starts the digestion of starch. The tongue moves food around the mouth and rolls it into a ball for swallowing. Taste buds are located on the tongue and in dogs and cats it is covered with spiny projections used for grooming and lapping. The cow’s tongue is prehensile and wraps around grass to graze it.

Swallowing is a complex reflex involving 25 different muscles. It pushes food into the oesophagus and at the same time a small flap of tissue called the epiglottis closes off the windpipe so food doesn’t go ‘down the wrong way’ and choke the animal (see diagram 11.4). Diagram 11.3 - Salivary glands Teeth[ edit ] Teeth seize, tear and grind food. They are inserted into sockets in the bone and consist of a crown above the gum and root below. The crown is covered with a layer of enamel, the hardest substance in the body. Below this is the dentine, a softer but tough and shock resistant material. At the centre of the tooth is a space filled with pulp which contains blood vessels and nerves. The tooth is cemented into the socket and in most teeth the tip of the root is quite narrow with a small opening for the blood vessels and nerves (see diagram 11.5). In teeth that grow continuously, like the incisors of rodents, the opening remains large and these teeth are called open rooted teeth. Mammals have 2 distinct sets of teeth. The first the milk teeth are replaced by the permanent teeth.

Diagram 11.5 - Structure of a tooth Types Of Teeth[ edit ] All the teeth of fish and reptiles are similar but mammals usually have four different types of teeth. The incisors are the chisel-shaped ‘biting off’ teeth at the front of the mouth. In rodents and rabbits the incisors never stop growing (open-rooted teeth). They must be worn or ground down continuously by gnawing. They have hard enamel on one surface only so they wear unevenly and maintain their sharp cutting edge. The largest incisors in the animal kingdom are found in elephants, for tusks are actually giant incisors. Sloths have no incisors at all, and sheep have no incisors in the upper jaw (see diagram 11.6). Instead there is a horny pad against which the bottom incisors cut. The canines or ‘wolf-teeth’ are long, cone-shaped teeth situated just behind the incisors. They are particularly well developed in the dog and cat families where they are used to hold, stab and kill the prey (see diagram 11.7).

The tusks of boars and walruses are large canines while rodents and herbivores like sheep have no (or reduced) canines. In these animals the space where the canines would normally be is called the diastema. In rodents like the rat and beaver it allows the debris from gnawing to be expelled easily. The cheek teeth or premolars and molars crush and grind the food. They are particularly well developed in herbivores where they have complex ridges that form broad grinding surfaces (see diagram 11.6). These are created from alternating bands of hard enamel and softer dentine that wear at different rates. In carnivores the premolars and molars slice against each other like scissors and are called carnassial teeth see diagram 11.7). They are used for shearing flesh and bone. Dental Formula[ edit ] The numbers of the different kinds of teeth can be expressed in a dental formula. This gives the numbers of incisors, canines, premolars and molars in one half of the mouth.

The numbers of these four types of teeth in the left or right half of the upper jaw are written above a horizontal line and the four types of teeth in the right or left half of the lower jaw are written below it. Thus the dental formula for the sheep is: 0.0.3.3 3.1.3.3 It indicates that in the upper right (or left) half of the jaw there are no incisors or canines (i.e. there is a diastema), three premolars and three molars. In the lower right (or left) half of the jaw are three incisors, one canine, three premolars and three molars (see diagram 11.6). Diagram 11.6 - A sheep’s skull The dental formula for a dog is: 3.1.4.2 3.1.4.3 The formula indicates that in the right (or left) half of the upper jaw there are three incisors, one canine, four premolars and two molars. In the right (or left) half of the lower jaw there are three incisors, one canine, four premolars and three molars (see diagram 11.7).

Diagram 11.7 - A dog’s skull Oesophagus[ edit ] The oesophagus transports food to the stomach. Food is moved along the oesophagus, as it is along the small and large intestines, by contraction of the smooth muscles in the walls that push the food along rather like toothpaste along a tube. This movement is called peristalsis (see diagram 11.8). Diagram 11.8 - Peristalsis Stomach[ edit ] The stomach stores and mixes the food. Glands in the wall secrete gastric juice that contains enzymes to digest protein and fats as well as hydrochloric acid to make the contents very acidic. The walls of the stomach are very muscular and churn and mix the food with the gastric juice to form a watery mixture called chyme (pronounced kime). Rings of muscle called sphincters at the entrance and exit to the stomach control the movement of food into and out of it (see diagram 11.9). Diagram 11.9 - The stomach Small Intestine[ edit ] Most of the breakdown of the large food molecules and absorption of the smaller molecules take place in the long and narrow small intestine.

The total length varies but it is about 6.5 metres in humans, 21 metres in the horse, 40 metres in the ox and over 150 metres in the blue whale. It is divided into 3 sections: the duodenum (after the stomach), jejunum and ileum. The duodenum receives 3 different secretions: 1) Bile from the liver; 2) Pancreatic juice from the pancreas and 3) Intestinal juice from glands in the intestinal wall. These complete the digestion of starch, fats and protein. The products of digestion are absorbed into the blood and lymphatic system through the wall of the intestine, which is lined with tiny finger-like projections called villi that increase the surface area for more efficient absorption (see diagram 11.10). Diagram 11.10 - The wall of the small intestine showing villi The Rumen[ edit ] In ruminant herbivores like cows, sheep and antelopes the stomach is highly modified to act as a “fermentation vat”. It is divided into four parts. The largest part is called the rumen.

In the cow it occupies the entire left half of the abdominal cavity and can hold up to 270 litres. The reticulum is much smaller and has a honeycomb of raised folds on its inner surface. In the camel the reticulum is further modified to store water. The next part is called the omasum with a folded inner surface. Camels have no omasum. The final compartment is called the abomasum. This is the ‘true’ stomach where muscular walls churn the food and gastric juice is secreted (see diagram 11.11). Diagram 11.11 - The rumen Ruminants swallow the grass they graze almost without chewing and it passes down the oesophagus to the rumen and reticulum. Here liquid is added and the muscular walls churn the food. These chambers provide the main fermentation vat of the ruminant stomach. Here bacteria and single-celled animals start to act on the cellulose plant cell walls. These organisms break down the cellulose to smaller molecules that are absorbed to provide the cow or sheep with energy. In the process, the gases methane and carbon dioxide are produced. These cause the “burps” you may hear cows and sheep making.

Not only do the micro-organisms break down the cellulose but they also produce the vitamins E, B and K for use by the animal. Their digested bodies provide the ruminant with the majority of its protein requirements. In the wild grazing is a dangerous activity as it exposes the herbivore to predators. They crop the grass as quickly as possible and then when the animal is in a safer place the food in the rumen can be regurgitated to be chewed at the animal’s leisure. This is ‘chewing the cud’ or rumination. The finely ground food may be returned to the rumen for further work by the microorganisms or, if the particles are small enough, it will pass down a special groove in the wall of the oesophagus straight into the omasum. Here the contents are kneaded and water is absorbed before they pass to the abomasum. The abomasum acts as a “proper” stomach and gastric juice is secreted to digest the protein. Large Intestine[ edit ] The large intestine consists of the caecum, colon and rectum.

The chyme from the small intestine that enters the colon consists mainly of water and undigested material such as cellulose (fibre or roughage). In omnivores like the pig and humans the main function of the colon is absorption of water to give solid faeces. Bacteria in this part of the gut produce vitamins B and K. The caecum, which forms a dead-end pouch where the small intestine joins the large intestine, is small in pigs and humans and helps water absorption. However, in rabbits, rodents and horses, the caecum is very large and called the functional caecum. It is here that cellulose is digested by micro-organisms. The appendix, a narrow dead end tube at the end of the caecum, is particularly large in primates but seems to have no digestive function. Functional Caecum[ edit ] The caecum in the rabbit, rat and guinea pig is greatly enlarged to provide a “fermentation vat” for micro-organisms to break down the cellulose plant cell walls. This is called a functional caecum (see diagram 11.12). In the horse both the caecum and the colon are enlarged.

As in the rumen, the large cellulose molecules are broken down to smaller molecules that can be absorbed. However, the position of the functional caecum after the main areas of digestion and absorption, means it is potentially less effective than the rumen. This means that the small molecules that are produced there can not be absorbed by the gut but pass out in the faeces. The rabbit and rodents (and foals) solve this problem by eating their own faeces so that they pass through the gut a second time and the products of cellulose digestion can be absorbed in the small intestine. Rabbits produce two kinds of faeces. Softer night-time faeces are eaten directly from the anus and the harder pellets you are probably familiar with, that have passed through the gut twice. Diagram 11.12 - The gut of a rabbit The Gut Of Birds[ edit ] Birds’ guts have important differences from mammals’ guts. Most obviously, birds have a beak instead of teeth. Beaks are much lighter than teeth and are an adaptation for flight. Imagine a bird trying to take off and fly with a whole set of teeth in its head!

At the base of the oesophagus birds have a bag-like structure called a crop. In many birds the crop stores food before it enters the stomach, while in pigeons and doves glands in the crop secretes a special fluid called crop-milk which parent birds regurgitate to feed their young. The stomach is also modified and consists of two compartments. The first is the true stomach with muscular walls and enzyme secreting glands. The second compartment is the gizzard. In seed eating birds this has very muscular walls and contains pebbles swallowed by the bird to help grind the food. This is the reason why you must always supply a caged bird with grit. In birds of prey like the falcon the walls of the gizzard are much thinner and expand to accommodate large meals (see diagram 11.13). Diagram 11.13 - The stomach and small intestine of a hen Digestion[ edit ] During digestion the large food molecules are broken down into smaller molecules by enzymes. The three most important groups of enzymes secreted into the gut are: Amylases that split carbohydrates like starch and glycogen into monosaccharides like glucose. Proteases that split proteins into amino acids.

Lipases that split lipids or fats into fatty acids and glycerol. Glands produce various secretions which mix with the food as it passes along the gut. These secretions include: Saliva secreted into the mouth from several pairs of salivary glands (see diagram 11.3). Saliva consists mainly of water but contains salts, mucous and salivary amylase. The function of saliva is to lubricate food as it is chewed and swallowed and salivary amylase begins the digestion of starch. Gastric juice secreted into the stomach from glands in its walls. Gastric juice contains pepsin that breaks down protein and hydrochloric acid to produce the acidic conditions under which this enzyme works best. In baby animals rennin to digest milk is also produced in the stomach. Bile produced by the liver. It is stored in the gall bladder and secreted into the duodenum via the bile duct (see diagram 11.14). (Note that the horse, deer, parrot and rat have no gall bladder). Bile is not a digestive enzyme.

Its function is to break up large globules of fat into smaller ones so the fat splitting enzymes can gain access the fat molecules. Diagram 11.14 - The liver, gall bladder and pancreas Pancreatic juice[ edit ] The pancreas is a gland located near the beginning of the duodenum (see diagram 11.14). In most animals it is large and easily seen but in rodents and rabbits it lies within the membrane linking the loops of the intestine (the mesentery) and is quite difficult to find. Pancreatic juice is produced in the pancreas. It flows into the duodenum and contains amylase for digesting starch, lipase for digesting fats and protease for digesting proteins. Intestinal juice[ edit ] Intestinal juice is produced by glands in the lining of the small intestine. It contains enzymes for digesting disaccharides and proteins as well as mucus and salts to make the contents of the small intestine more alkaline so the enzymes can work. Absorption[ edit ] The small molecules produced by digestion are absorbed into the villi of the wall of the small intestine. The tiny finger-like projections of the villi increase the surface area for absorption.

Glucose and amino acids pass directly through the wall into the blood stream by diffusion or active transport. Fatty acids and glycerol enter vessels of the lymphatic system (lacteals) that run up the centre of each villus. The Liver[ edit ] The liver is situated in the abdominal cavity adjacent to the diaphragm (see diagrams 2 and 14). It is the largest single organ of the body and has over 100 known functions. Its most important digestive functions are: the production of bile to help the digestion of fats (described above) and the control of blood sugar levels Glucose is absorbed into the capillaries of the villi of the intestine. The blood stream takes it directly to the liver via a blood vessel known as the hepatic portal vessel or vein (see diagram 11.15). The liver converts this glucose into glycogen which it stores. When glucose levels are low the liver can convert the glycogen back into glucose. It releases this back into the blood to keep the level of glucose constant. The hormone insulin, produced by special cells in the pancreas, controls this process.

Diagram 11.15 - The control of blood glucose by the liver Other functions of the liver include: 3. making vitamin A, 4. making the proteins that are found in the blood plasma (albumin, globulin and fibrinogen), 5. storing iron, 6. removing toxic substances like alcohol and poisons from the blood and converting them to safer substances, 7. producing heat to help maintain the temperature of the body. Diagram 11.16 - Summary of the main functions of the different regions of the gut Summary[ edit ] The gut breaks down plant and animal materials into nutrients that can be used by animals’ bodies. Plant material is more difficult to break down than animal tissue. The gut of herbivores is therefore longer and more complex than that of carnivores. Herbivores usually have a compartment (the rumen or functional caecum) housing micro-organisms to break down the cellulose wall of plants. Chewing by the teeth begins the food processing. There are 4 main types of teeth: incisors, canines, premolars and molars.

In dogs and cats the premolars and molars are adapted to slice against each other and are called carnassial teeth. Saliva is secreted in the mouth. It lubricates the food for swallowing and contains an enzyme to break down starch. Chewed food is swallowed and passes down the oesophagus by waves of contraction of the wall called peristalsis. The food passes to the stomach where it is churned and mixed with acidic gastric juice that begins the digestion of protein. The resulting chyme passes down the small intestine where enzymes that digest fats, proteins and carbohydrates are secreted. Bile produced by the liver is also secreted here. It helps in the breakdown of fats. Villi provide the large surface area necessary for the absorption of the products of digestion. In the colon and caecum water is absorbed and micro organisms produce some vitamin B and K. In rabbits, horses and rodents the caecum is enlarged as a functional caecum and micro-organisms break down cellulose cell walls to simpler carbohydrates. Waste products exit the body via the rectum and anus. The pancreas produces pancreatic juice that contains many of the enzymes secreted into the small intestine.

In addition to producing bile the liver regulates blood sugar levels by converting glucose absorbed by the villi into glycogen and storing it. The liver also removes toxic substances from the blood, stores iron, makes vitamin A and produces heat. Worksheet[ edit ] Use the Digestive System Worksheet to help you learn the different parts of the digestive system and their functions. Test Yourself[ edit ] Then work through the Test Yourself below to see if you have understood and remembered what you learned. 1. Name the four different kinds of teeth 2. Give 2 facts about how the teeth of cats and dogs are adapted for a carnivorous diet: 1. 3. What does saliva do to the food? 4. What is peristalsis? 5. What happens to the food in the stomach? 6. What is chyme? 7. Where does the chyme go after leaving the stomach? 8. What are villi and what do they do? 9. What happens in the small intestine? 10. Where is the pancreas and what does it do? 11. How does the caecum of rabbits differ from that of cats? 12. How does the liver help control the glucose levels in the blood? 13.

Give 2 other functions of the liver: 1. Drs. Foster and Smith Cleansing Pads Variety 3-Pack As low as $14.39 If you look inside your dog's mouth you will notice one tooth that is much larger than the rest. It is on the upper jaw, about half way back. It is the fourth premolar, sometimes referred to as the carnassial tooth. In wild canines, it is the main tooth used to break up or crush hard material in their diet such as bones or large pieces of meat. Today's canine diets, even the all-dry ones, really do not require this big "work horse" tooth for the animal to adequately break up his food before swallowing. Still, it is there, and it poses some unique problems for the older dog. Signs and development of a carnassial tooth abscess An infection of the 4th premolar is a unique dental problem and has outward signs that are often misunderstood by the owner. The large carnassial tooth has three roots while most other teeth have only 1 or 2.

From ½" to ¾" long, they extend from below the gumline up into the bone of the skull just in front of the eye. There are two in the front portion of the tooth and one in the rear. Carnassial tooth infections actually involve only the roots of the tooth and not the visible exposed portion. The individual root usually involved is the front one that is closest to the skin. Carnassial tooth infections are caused by bacteria that gain access to the root, either by working their way under the gum at the base of the tooth or by being carried there by the bloodstream. Once the bacteria are in this location between the root and the bone of the skull, the body has a very difficult time ridding itself of the infection. Treatment may control the outward signs but when the medication is discontinued, the infection returns. The bacteria take up residence on the surface of the root and slowly destroy its attachment to the jaw. In doing so, they deprive the root, and therefore, the tooth, of its blood supply. This eventually leads to death of the affected tissue. Dead tissue in the body is treated the same way as a splinter or other foreign material.

In an attempt to isolate and repel the material, the body shunts millions of white blood cells into the area to: Isolate it from the remaining healthy tissue Dissolve or break it down so that it can be eliminated as typical cellular waste Expel it whole from the body This accumulation of white blood cells at the site of an infection or necrotic material is referred to as pus or an abscess. In the case of a carnassial tooth, the abscess builds up around the affected root just under the skin below and in front of the eye. The swelling may reach the size of a golf ball. In the case of an abscess, the white blood cells and chemicals that are released have the ability to dissolve the body's tissue. The weakest portion of the body in this case is the skin, so a small pore soon opens from which pus (or a pink-tinged fluid) will drain. Left alone, this opening will occasionally close, but then reopen later as more material accumulates. Owners often confuse this condition with an eye infection, insect bite, or puncture wound. They may consider it something that, if left alone, will heal on its own.

The untreated abscess will, in fact, often spread to 1) the eye causing a very serious and potentially blinding infection or 2) other teeth causing them to be lost also. This is fairly painful for the animal, especially when eating. In dogs that stay outdoors or those with long hair, it may remain unnoticed for a long period of time. Treatment options Carnassial abscesses are typically seen in older dogs, especially those over seven years of age. By the time we are able to actually recognize a problem, the initially affected root is often dead. Today, veterinary medicine allows the owner to choose between several methods for handling this problem. There was only one option in the past - pull the tooth along with its roots. The tooth is actually split in half so that the roots can be entirely removed. This is the most difficult tooth to remove correctly and if any portion of the root remains, the problem may continue. Veterinarians today can save the tooth with a procedure similar to the 'root canal.' This can be fairly expensive, but it does save the tooth. Either therapy choice is followed by a long-term use of antibiotics to prevent future problems.

When determining which method to use for your animal, keep in mind 1) the cost, 2) the dog's dental health and overall health, and 3) the effect the loss of the tooth would have on your pet. In most cases, a dog does just fine without this particular tooth and is able to eat any type of food you may choose to give him. Related Information:

Question: What type of food is eaten by animals with carnassial teeth?
Answer: Meat